Information recording device and method, information reproducing device and method, recording medium, program, and disc recording medium

ABSTRACT

An ECC block is constituted by RS(248, 216, 33). Of a data length of 216 bytes (symbols), only 16 bytes are allocated to BCA data and the remaining 200 bytes are used for fixed data having a predetermined value. Using the fixed data of 200 bytes and the BCA data of 16 bytes, parities of 32 bytes (symbols) are calculated. Only the BCA data of 16 bytes and the parities of the former 16 bytes of the 32-byte parities, that is, a total of 32 bytes only, are recorded in a burst cutting area of an optical disc. In decoding, error correction processing is carried out by using the fixed data of 200 bytes. The unrecorded parities of 16 bytes are processed as having been erased. Thus, the error correction capability in a burst cutting area of an optical disc can be improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of Ser. No.10/472,707 filed Mar. 29, 2004, which is the National Stage ofPCT/JP03/00683 filed Jan. 24, 2003, the entire contents of which areincorporated herein by reference. This application claims priority ofJapanese Patent Application No. 2002-017247 filed on Jan. 25, 2002, theentirety of which is incorporated by reference herein.

TECHNICAL FIELD

This invention relates to an information recording device and method, aninformation reproducing device and method, a recording medium, aprogram, and a disc recording medium, and particularly to an informationrecording device and method which enables recording of a plurality ofdisc IDs, an information reproducing device and method, a recordingmedium, a program, and a disc recording medium.

BACKGROUND ART

As a disc recording medium on which, for example, digital data such as ahigh-quality digital video signal is optically recorded, a playback-onlyDVD (digital versatile disc or digital video disc) has been broadlyknown. Moreover, as disc recording media which enable writing once orrewriting by using the DVD format, a DVD-R (DVD-recordable), a DVD-RW(DVD-rewritable) and a DVD-RAM (DVD-random access memory) are beingpopularized.

Furthermore, a next-generation optical disc is to be commercializedwhich can realize a large capacity of approximately more than 23gigabytes with a track pitch of 0.32 μm, a scanning density of 0.12μm/bit and a diameter of 120 mm, by using a combination of a blue laserbeam with a wavelength of 405 nm and an objective lens with NA of 0.85.With respect to this next-generation optical disc, a recording layer isformed on a substrate, and a transparent cover layer with a thickness ofapproximately 0.1 mm is formed on the recording layer. The transparentcover layer has an excellent optical characteristic and it ishard-coated so as to be scratch-proof, for example. The laser beam iscast onto the recording layer via the transparent cover layer having theabove-described thickness of 0.1 mm.

By reducing the thickness of the transparent cover layer, the spotdiameter of the laser beam on the recording layer can be reduced.However, if the spot diameter is thus reduced, the optical disc becomesmore susceptible to a dust particle of a size which would not cause anyproblem when the spot diameter is large.

Therefore, in the case of recording data onto the next-generationoptical disc with a thin transparent cover layer, reinforcement of anerror correcting code is necessary. This also applies to a BCA (burstcutting area) on an optical disc where the disc ID is recorded, as wellas a data area where content data is recorded.

However, if the error correcting code in the BCA is to be reinforced,the redundancy is increased and the quantity of recordable data isreduced.

On the other hand, if the redundancy is reduced, the error correctioncapability is lowered.

DISCLOSURE OF THE INVENTION

In view of the foregoing status of the art, it is an object of thepresent invention to provide high error correction capability withoutincreasing the redundancy.

A first information recording device according to the present inventioncomprises: acquisition means for acquiring auxiliary information;blocking means for blocking the auxiliary information acquired by theacquisition means to generate error correction blocks, using an errorcorrecting code that is the same as an error correcting code RS(m,n,k)of main data recorded in a data area, with data having a length d whichis smaller than the n and fixed data having the remaining length n-d;modulation means for modulating the error correction blocks generated bythe blocking means; and recording means for recording the errorcorrection blocks modulated by the modulation means, into a burstcutting area on a disc recording medium.

The modulation means may modulate only a part of parities having alength of k−1 of the error correction blocks.

The modulation means may modulate only parities of (k−1)/2, which are apart of parities having a length of k−1 of the error correction blocks.

The blocking means may use RS(248, 216, 33) as the error correcting codeRS(m,n,k).

A first information recording method according to the present inventioncomprises: an acquisition step of acquiring auxiliary information; ablocking step of blocking the auxiliary information acquired by theprocessing of the acquisition step to generate error correction blocks,using an error correcting code that is the same as an error correctingcode RS(m,n,k) of main data recorded in a data area, with data having alength d which is smaller than the n and fixed data having the remaininglength n-d; a modulation step of modulating the error correction blocksgenerated by the processing of the blocking step; and a recording stepof recording the error correction blocks modulated by the processing ofthe modulation step, into a burst cutting area on a disc recordingmedium.

A program on a first recording medium according to the present inventionis a program adapted for an information recording device which recordsauxiliary data onto a disc recording medium having data area forrecording main data and a burst cutting area for recording the auxiliaryinformation proper to the disc recording medium, the program comprising:an acquisition step of acquiring the auxiliary information; a blockingstep of blocking the auxiliary information acquired by the processing ofthe acquisition step to generate error correction blocks, using an errorcorrecting code that is the same as an error correcting code RS(m,n,k)of the main data recorded in the data area, with data having a length dwhich is smaller than the n and fixed data having the remaining lengthn-d; a modulation step of modulating the error correction blocksgenerated by the processing of the blocking step; and a recording stepof recording the error correction blocks modulated by the processing ofthe modulation step, into the burst cutting area on the disc recordingmedium.

A first program according to the present invention is executable by acomputer which controls an information recording device for recordingauxiliary information onto a disc recording medium having a data areafor recording main data and a burst cutting area for recording theauxiliary information proper to the disc recording medium, the programcomprising: an acquisition step of acquiring the auxiliary information;a blocking step of blocking the auxiliary information acquired by theprocessing of the acquisition step to generate error correction blocks,using an error correcting code that is the same as an error correctingcode RS(m,n,k) of the main data recorded in the data area, with datahaving a length d which is smaller than the n and fixed data having theremaining length n-d; a modulation step of modulating the errorcorrection blocks generated by the processing of the blocking step; anda recording step of recording the error correction blocks modulated bythe processing of the modulation step, into the burst cutting area onthe disc recording medium.

A disc recording medium according to the present invention has auxiliaryinformation recorded in its burst cutting area, wherein the auxiliaryinformation is coded, using an error correcting code that is the same asan error correcting code RS(m,n,k) of the main data recorded in the dataarea, with data having a length d which is smaller than the n and fixeddata having the remaining length n-d.

A second information recording device according to the present inventioncomprises: first acquisition means for acquiring auxiliary informationrecorded in a burst cutting area, the auxiliary information beingblocked to generate error correction blocks, using an error correctingcode that is the same as an error correcting code RS(m,n,k) of main datarecorded in a data area, with data having a length d which is smallerthan the n and fixed data having the remaining length n-d; secondacquisition means for acquiring the main data; encryption means forencrypting the main data acquired by the second acquisition means on thebasis of the auxiliary information acquired by the first acquisitionmeans; modulation means for modulating the main data encrypted by theencryption means; and recording means for recording the main datamodulated by the modulation means into the data area on the discrecording medium.

Only a part of parities having a length of k−1 of the error correctionblocks may be encoded.

Only parities of (k−1)/2, which are a part of parities having a lengthof k−1, of the error correction blocks may be encoded.

The error correcting code RS(m,n,k) may be RS(248, 216, 33).

A second information recording method according to the present inventioncomprises: a first acquisition step of acquiring auxiliary informationrecorded in a burst cutting area, the auxiliary information beingblocked to generate error correction blocks, using an error correctingcode that is the same as an error correcting code RS(m,n,k) of main datarecorded in a data area, with data having a length d which is smallerthan the n and fixed data having the remaining length n-d; a secondacquisition step of acquiring the main data; an encryption step ofencrypting the main data acquired by the processing of the secondacquisition step on the basis of the auxiliary information acquired bythe processing of the first acquisition step; a modulation step ofmodulating the main data encrypted by the processing of the encryptionstep; and a recording step of recording the main data modulated by theprocessing of the modulation step into the data area on the discrecording medium.

A program on a second recording medium according to the presentinvention is a program adapted for an information recording device whichrecord main data onto a disc recording medium having a data area forrecording the main data and a burst cutting area for recording auxiliaryinformation proper to the disc recording medium, the program comprising:a first acquisition step of acquiring the auxiliary information recordedin the burst cutting area, the auxiliary information being blocked togenerate error correction blocks, using an error correcting code that isthe same as an error correcting code RS(m,n,k) of the main data recordedin the data area, with data having a length d which is smaller than then and fixed data having the remaining length n-d; a second acquisitionstep of acquiring the main data; an encryption step of encrypting themain data acquired by the processing of the second acquisition step onthe basis of the auxiliary information acquired by the processing of thefirst acquisition step; a modulation step of modulating the main dataencrypted by the processing of the encryption step; and a recording stepof recording the main data modulated by the processing of the modulationstep into the data area on the disc recording medium.

A second program according to the present invention is executable by acomputer which controls an information recording device for recordingmain data onto a disc recording medium having a data area for recordingthe main data and a burst cutting area for recording auxiliaryinformation proper to the disc recording medium, the program comprising:a first acquisition step of acquiring the auxiliary information recordedin the burst cutting area, the auxiliary information being blocked togenerate error correction blocks, using an error correcting code that isthe same as an error correcting code RS(m,n,k) of the main data recordedin the data area, with data having a length d which is smaller than then and fixed data having the remaining length n-d; a second acquisitionstep of acquiring the main data; an encryption step of encrypting themain data acquired by the processing of the second acquisition step onthe basis of the auxiliary information acquired by the processing of thefirst acquisition step; a modulation step of modulating the main dataencrypted by the processing of the encryption step; and a recording stepof recording the main data modulated by the processing of the modulationstep into the data area on the disc recording medium.

An information reproducing device according to the present inventioncomprises: acquisition means for acquiring auxiliary informationrecorded in a burst cutting area, the auxiliary information beingblocked to generate error correction blocks, using an error correctingcode that is the same as an error correcting code RS(m,n,k) of main datarecorded in a data area, with data having a length d which is smallerthan the n and fixed data having the remaining length n-d; reproductionmeans for reproducing the main data from the data area; demodulationmeans for demodulating the main data reproduced by the reproductionmeans; and decoding means for decoding the main data demodulated by thedemodulation means on the basis of the auxiliary information acquired bythe acquisition means.

Only a part of parities having a length of k−1 of the error correctionblocks may be encoded.

Only parities of (k−1)/2, which are a part of parities having a lengthof k−1, of the error correction blocks may be encoded.

The error correcting code RS(m,n,k) may be RS(248, 216, 33).

If the plurality of error correction blocks are recorded on the discrecording medium, the acquisition means may select a predetermined errorcorrection block on the basis of the identification number and the blocknumber recorded in a header of the error correction blocks and acquirethe auxiliary information of the selected error correction block.

If an error of the selected error correction block of the plurality oferror correction blocks cannot be corrected, the acquisition means mayselect another error correction block having the correspondingidentification number and block number.

An information reproducing method according to the present inventioncomprises: an acquisition step of acquiring auxiliary informationrecorded in a burst cutting area, the auxiliary information beingblocked to generate error correction blocks, using an error correctingcode that is the same as an error correcting code RS(m,n,k) of main datarecorded in a data area, with data having a length d which is smallerthan the n and fixed data having the remaining length n-d; areproduction step of reproducing the main data from the data area; ademodulation step of demodulating the main data reproduced by theprocessing of the reproduction step; and a decoding step of decoding themain data demodulated by the processing of the demodulation step on thebasis of the auxiliary information acquired by the processing of theacquisition step.

A program on a third recording medium according to the present inventionis a program adapted for an information reproducing device whichreproduces main data from a disc recording medium having a data area inwhich the main data is recorded and a burst cutting area in whichauxiliary information proper to the disc recording medium is recorded,the program comprising: an acquisition step of acquiring the auxiliaryinformation recorded in the burst cutting area, the auxiliaryinformation being blocked to generate error correction blocks, using anerror correcting code that is the same as an error correcting codeRS(m,n,k) of the main data recorded in the data area, with data having alength d which is smaller than the n and fixed data having the remaininglength n-d; a reproduction step of reproducing the main data from thedata area; a demodulation step of demodulating the main data reproducedby the processing of the reproduction step; and a decoding step ofdecoding the main data demodulated by the processing of the demodulationstep on the basis of the auxiliary information acquired by theprocessing of the acquisition step.

A third program according to the present invention is executable by acomputer which controls an information reproducing device forreproducing main data from a disc recording medium having a data area inwhich the main data is recorded and a burst cutting area in whichauxiliary information proper to the disc recording medium is recorded,the program comprising: an acquisition step of acquiring the auxiliaryinformation recorded in the burst cutting area, the auxiliaryinformation being blocked to generate error correction blocks, using anerror correcting code that is the same as an error correcting codeRS(m,n,k) of the main data recorded in the data area, with data having alength d which is smaller than the n and fixed data having the remaininglength n-d; a reproduction step of reproducing the main data from thedata area; a demodulation step of demodulating the main data reproducedby the processing of the reproduction step; and a decoding step ofdecoding the main data demodulated by the processing of the demodulationstep on the basis of the auxiliary information acquired by theprocessing of the acquisition step.

In the first information recording device and method, recording mediumand program according to the present invention, the auxiliaryinformation in the burst cutting area is error-corrected and blocked byusing the error correcting code that is the same as the error correctingcode RS(m,n,k) of the main data recorded in the data area, with datahaving a length d which is smaller than the n and fixed data having theremaining length n-d.

In the disc recording medium according to the present invention, theauxiliary information is error-corrected and blocked by using the errorcorrecting code that is the same as the error correcting code RS(m,n,k)of the main data recorded in the data area, with data having a length dwhich is smaller than the n and fixed data having the remaining lengthn-d, and the blocked auxiliary information is recorded in the burstcutting area.

In the second information recording device and method, recording mediumand program according to the present invention, the main data isencrypted on the basis of the auxiliary information which iserror-corrected and blocked by using the error correcting code that isthe same as the error correcting code RS(m,n,k) of the main datarecorded in the data area, with data having a length d which is smallerthan the n and fixed data having the remaining length n-d, and theencrypted main data is recorded in the data area.

In the information reproducing device and method, recording medium andprogram according to the present invention, the auxiliary information iserror-corrected and blocked by using the error correcting code that isthe same as the error correcting code RS(m,n,k) of the main datarecorded in the data area, with data having a length d which is smallerthan the n and fixed data having the remaining length n-d. The main datais decoded on the basis of this auxiliary information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a disc format of an optical disc to which the presentinvention is applied.

FIG. 2 illustrates 4/1 modulation.

FIG. 3 illustrates the relation between a channel and a mark.

FIG. 4 illustrates the structure of BCA data.

FIG. 5 shows an example of frame sync.

FIG. 6 illustrates the structure of an ECC block in a burst cuttingarea.

FIG. 7 illustrates the structure of an ECC block in a data area.

FIG. 8 illustrates a recording format of a BCA code.

FIG. 9 illustrates a BCA content code.

FIG. 10 shows the relation between a bit error rate of raw data and anerror rate of a BCA code.

FIG. 11 illustrates the structure of an ECC block of 64 kilobytes in thedata area.

FIG. 12 shows the relation between a raw symbol error rate and acorrected symbol error rate.

FIG. 13 shows another structure of the ECC block.

FIG. 14 is a block diagram showing the structure of a disc recordingdevice for recording a BCA code into the burst cutting area.

FIG. 15 is a flowchart for explaining BCA recording processing at thedisc recording device of FIG. 14.

FIG. 16 is a block diagram showing the structure of a discrecording/reproducing device to which the present invention is applied.

FIG. 17 is a flowchart for explaining data recording processing at thedisc recording/reproducing device of FIG. 16.

FIG. 18 is a flowchart for explaining the details of BCA reproductionprocessing at step S31 of FIG. 17.

FIG. 19 is a flowchart for explaining data reproduction processing atthe disc recording/reproducing device of FIG. 16.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will now be described withreference to the drawings.

An embodiment of the disc recording medium according to the presentinvention is a next-generation optical disc which can realize a largecapacity of more than 23.3 gigabytes with a diameter of 120 mm. Withrespect to this next-generation optical disc, a recording layer isformed on a substrate, and a transparent cover layer with a thickness of0.1 mm is formed on the recording layer. For recording and reproducingcontent data, for example, a blue-violet laser beam with a wavelength of405 nm is condensed by an optical pickup with a numerical aperture setat NA=0.85 and is cast onto the recording layer via the transparentcover layer having a thickness of 0.1 mm.

FIG. 1 shows the disc format of an optical disc 1 to which the presentinvention is applied. A burst cutting area (BCA) 1A is concentricallyformed in a range from a radium of 21.3 mm to a radius of 22.0 mm on theouter side (in this example, on the inner side) of a data area 1B wherecontent data (such as AV data) is recorded, on the inner circle of theoptical disc 1. In this BCA, auxiliary information including attributeinformation such as disc ID information proper to the disc is recordedover 4648 channels, of 4750 channels (channel bits) per circle.

FIG. 2 shows a modulation method for data recorded in the burst cuffingarea 1A. In this example, source data of 2 bits is modulated tomodulation data of 7 bits. The modulation data of 7 bits is made up of asynchronizing part of 3 bits followed by a data part of 4 bits.

The synchronizing part has bits “010”. In the data part, one of the 4bits is set to “1”. In the example of FIG. 2, the data part of sourcedata “00” is set to “1000”. The data part of source data “01” is set to“0100”. The data part of source data “10” is set to “0010”. And the datapart of source data “11” is set to “0001”.

Thus, in this modulation method, one of four channel bits is selected.Hereinafter, this modulation method is referred to as 4/1 modulation.

FIG. 3 schematically shows the state where a synchronizing part and adata part are recorded in the burst cutting area 1A. The length L1 (inthe circumferential direction of the disc) of one channel bit isapproximately 30 μm. On the other hand, in a channel bit for which “1”is recorded, a mark with a length L2 of approximately 10 to 15 μm isrecorded. This mark is not formed in a channel of “0”, which is simply aspace.

In the example of FIG. 3, data having channel bits of “0101000” (datahaving channels bits corresponding to the source data “00” in FIG. 2) ispresented.

FIG. 4 shows the data structure of the data recorded in the burstcutting area 1A. As shown in FIG. 4, each frame (line) is made up of 5bytes. The leading 1 byte of each frame is a frame sync and the 4 bytesfollowing the frame sync constitute data.

The frame sync of the first frame is set to SB_(BCA,−1) and the data isa preamble. All the value of the preamble is 00h. Using this preamble, achannel clock is generated by a PLL, which will be described later.

Since the frame sync SB_(BCA,−1) of the first frame has a unique value,the start position of the BCA code can be detected by using this framesync. Alternatively, both the frame sync SB_(BCA,−1) and the subsequentpreamble can be detected as the start position of the BCA code.

The second to 33^(rd) frames are sectioned by four frames each. As thedata of the second to fifth frames, user data I_(0,0,) to I_(0,15) of 16bytes are arranged. In the subsequent sixth to ninth frames, paritiesC_(0,0) to C_(0,15) of 16 bytes corresponding to the user data I_(0,0)to I_(0,15) of the second to fifth frames are arranged.

One ECC block is constituted on the basis of the user data of the secondto fifth frames and the parity data of the sixth to ninth frames.

Similarly, user data I_(1,0) to I_(1,15) are arranged in the 10^(th) to13^(th) frames and parities C_(1,0) to C_(1,15) corresponding to theuser data are arranged in the 14^(th) to 17^(th) frames. User dataI_(2,0) to I_(2,15) are arranged in the 18^(th) to 21^(st) frames andcorresponding parities C_(2,0) to C_(2,15) are arranged in the 22^(nd)to 25^(th) frames. User data I_(3,0) to I_(3,15) are arranged in the26^(th) to 29^(th) frames and corresponding parities C_(3,0) to C_(3,5)are arranged in the 30^(th) to 33^(rd) frames.

The frame syncs of the second to fifth frames are set to SB_(BCA,0). Theframe syncs of the sixth to ninth frames are set to SB_(BCA,1). Theframe syncs of the 10^(th) to 13^(th) frames are set to SB_(BCA,2). Theframe syncs of the 14^(th) to 17^(th) frames are set to SB_(BCA,3). Theframe syncs of the 18^(th) to 21^(st) frames are set to SB_(BCA,4). Theframe syncs of the 22^(nd) to 25^(th) frames are set to SB_(BCA,5). Theframe syncs of the 26^(th) to 29^(th) frames are set to SB_(BCA,6). Theframe syncs of the 30^(th) to 33^(rd) frames are set to SB_(BCA,7).

The frame sync of termination of the 34^(th) frame is set toSB_(BCA,−2). The 34^(th) frame has no data arranged therein and only hasthe frame sync.

The data of FIG. 4 represents data before being 4/1-modulated inaccordance with the modulation method of FIG. 2. The total quantity ofdata is 166 (=5×4×8+5+1) bytes. As a result of modulating the data of166 bytes by 4/1 modulation shown in FIG. 2, 4648 (=166×8×7/2) channelbits are provided (FIG. 1).

FIG. 5 shows a specific example of the frame syncs shown in FIG. 4. Theexample shown in FIG. 5 represents the structure of channel bits afterbeing 4/1-modulated.

A frame sync of 28 channel bits is made up of a sync body of 14 channelbits and sync ID of 14 channel bits.

The sync body of 14 channel bits is made up of a sync body 1 of 7channel bits and a sync body 2 of 7 channel bits. The sync ID of 14channel bits is made up of sync ID 1 of 7 channel bits and sync ID 2 of7 channel bits.

The sync body has an out-of-rule pattern of 4/1 modulation.Specifically, as shown in FIG. 2, in the case of 4/1 modulation, thevalue of the synchronizing part is set to “010”. However, thesynchronizing part of the sync body 2 is not “010” but “001”. Therefore,it is possible to easily identify the frame sync from the data.

The sync body 1 of each frame sync is set to “010 0001” and the syncbody 2 is set to “001 0100”.

On the other hand, the sync IDs of the respective frame syncs havedifferent values, thus making it possible to identify the frame syncsfrom each other.

Specifically, in the example of FIG. 5, the sync ID of SB_(BCA,−1) ofthe preamble and the sync ID of the frame sync SB_(BCA,−2) of thetermination are set to “010 0001”. Therefore, the preamble and thetermination can be easily identified from the other frames. Since thesync ID 2 of the preamble frame has a value “010 0001” and the sync ID 2of the terminal frame has a value “0100010”, the preamble frame and thetermination frame can be identified from each other.

Moreover, the frame syncs of the other frames can be identified from oneanother because they have different values, as shown in FIG. 5.

FIG. 6 shows the structure of an ECC block of a BCA code constituted asshown in FIG. 4. Specifically, a Reed-Solomon code of RS(248, 216, 33)is used as an ECC code. The code has a code length m of 248 bytes(symbols), a data length n of 216 bytes (symbols) and a distance of 33bytes (symbols).

This ECC block of the BCA code is constituted similarly to an ECC blockof content data, which is main data recorded in the data area 1B shownin FIG. 1.

Specifically, as the ECC block in the data area 1B, again, aReed-Solomon code of RS(248, 216, 33) is used, as shown in FIG. 7.

However, in the ECC block of the BCA code, the leading 200 bytes(symbols) of the data length n of 216 bytes are fixed data, and anarbitrary value such as FFh is used, as shown in FIG. 6. The 16 bytes(symbols) I₀ to I₁₅ after the fixed data are user data substantiallyconstituting the BCA data.

Although the BCA data is arranged at the trailing end of the 216 bytes(symbols) in FIG. 6, it may be arranged at the leading end.

Using the fixed data of 200 bytes and the BCA data of 16 bytes, paritiesof 32 bytes are calculated. If the fixed data of 200 bytes does notexist, the parities of 32 bytes cannot be calculated. Since the fixeddata of 200 bytes is thus used as the base for calculating the parity,it is not simply stuffing data.

Moreover, in the present invention, only the parities C₀ to C₁₅ of theleading 16 bytes are recorded on the optical disc 1 and the parities ofthe remaining 16 bytes are not recorded.

Of the data of 216 bytes (symbols), the fixed data of 200 bytes is notrecorded and only the BCA data of 16 bytes is recorded. After all, ofthe ECC block of 248 bytes, only the BCA data of 16 bytes and theparities of 16 bytes, that is, a total of 32 bytes (symbols), arerecorded.

As a result, the error correction performance corresponds to the errorcorrection performance of RS(32, 16, 17).

In decoding, the same value is used as it is for the fixed data of 200bytes. The unrecorded parities of 16 bytes are decoded as pointererasure. That is, of the parities of 32 bytes, the parities of thelatter 16 bytes are processed as having been erased. Even if a half ofthe parities are erased, their positions are known and therefore theoriginal parities can be decoded.

By thus using the same RS(248, 216, 33) as the ECC of the main datarecorded in the data area 1B, very high error correction capability canbe realized for the BCA code in the burst cutting area 1A. Since ECCprocessing of the BCA code can be carried out by using the same hardwareas for the ECC of the main data in the data area 1B, simplification ofthe structure and reduction in cost can be realized. Moreover, since itsuffices to record only 32 symbols, the scanning density can beincreased in comparison with the case of recording all the 248 symbolsand the detection is made easier, thus improving the reliability. It isalso possible to record a large volume of data (disc ID).

FIG. 8 shows the structure of the ECC block of the BCA. As shown in FIG.8, in the present invention, four ECC blocks are recorded in the burstcutting area 1A.

Data of 16 bytes of each ECC block is made up of a header of leading 2bytes followed by content data of 14 bytes. The header is made up of aBCA content code of 1 byte and a content data length of 1 byte.

In the BCA content code, 6 bits from a leading bit 7 to a bit 2constitute application ID, and 2 bits, that is, the last bit 1 and a bit0, constitute the block number, as shown in FIG. 9.

The optical disc recording/reproducing device is capable of recordingand reproducing data to and from only an optical disc provided with theBCA code having application ID set in advance. For example, datanecessary to protect content data (such as key information forencrypting/decrypting content data or disc ID) can be recorded to theBCA code having specific application ID.

The block number is one of four numbers “00”, “01”, “10” and “11”.

If the content data of every ECC block has 14 bytes or less, every ECCblock has the block number “00”.

On the other hand, if the same content data is recorded, for example, asthe content data of each of the leading two ECC blocks of the four ECCblocks (that is, if the same content data having the same application IDis double-written), each of the two ECC blocks has the block number“00”. That is, in case of recording the same content data, the blocknumber of the two ECC blocks are the same number.

If content data having different application ID from the application IDof the first two ECC blocks is recorded consecutively throughout 24bytes in the remaining (latter) two ECC blocks, the first ECC block ofthe latter two ECC blocks has the block number “00” and the second ECCblock has the block number “01”. That is, in case of recording contentdata over a plurality of ECC blocks, the block number of each ECC blockis the serial number. Each of the latter two ECC blocks has a contentdata length with a value of 24 bytes (which is the actual length of theuser data).

On contrary, if the same content data is double-written, each of the ECCblocks have a content data length of 14 bytes (fixed length).

If the content data is less than 14 bytes, stuffing data is added andeach ECC block has a content data size of 14 bytes (fixed length).

Since the application ID and the block number are thus recorded in eachECC block, it can be identified which ECC block has desired data storedtherein and whether the content data is multiple-written or singlywritten.

The BCA content code, the content data length and the content data (16bytes) of the leading ECC block of FIG. 8 correspond to I_(0,0) toI_(0,15) (16 bytes) of the leading ECC block of FIG. 4. Similarly, theBCA content codes, the content data length and the content data of thesecond to fourth ECC blocks of FIG. 8 correspond to I₀ to I₁₅ of thesecond to fourth ECC blocks of FIG. 4, respectively.

FIG. 10 shows the error correction capability of the BCA code. In FIG.10, a curve A represents the error rate in the case where the same datais recorded in each of four ECC blocks (quadruple writing), and a curveB represents the error rate of an error generated in one of four ECCblocks in the case where different data are recorded in the four ECCblocks (single writing).

As the optical disc 1 with the cover layer having a thickness of 0.1 mmis inserted in the cartridge and the degree of adherence of dustparticles is examined, the adherence of dust particles is found inapproximately 0.1% of the entire area. Thus, the error rate of the BCAcode with respect to the bit error rate of 0.1% (=1 E-3=1×10-3) isapproximately 1.0×E-12 for the curve B, and a much smaller value for thecurve A.

In FIG. 10, the horizontal axis represents the bit error rate of rawdata and the vertical axis represents the error rate of the BCA code.

The error correction block of main data (content data) such as AV datarecorded in the data area 1B is constituted by a 64-kilobyte unit, asshown in FIG. 1. By thus expanding the structure of the ECC block, theinterleave length can be increased and higher resistance to burst errorsis provided.

In this case, the unit of recording and reproduction may be a 2-kilobytesector unit. While recording or reproducing data with an errorcorrection block of a 64-kilobyte unit, a desired 2-kilobyte sector isrecorded or reproduced therefrom.

The error correcting code is RS(248, 216, 33) and one error correctionblock is made up of 304 correcting codes.

If an error detecting code (EDC) of 4 bytes is added to data of 2kilobytes (=2048 bytes), the total quantity of data is 2052 bytes. Onthe assumption that one sector is made up of data of 2052 bytes, 322-kilobyte sectors can be formed in the error correction block of 64kilobytes as a unit. Therefore, the quantity of data of the errorcorrection block of 64 kilobytes is 65664 (=2052×32) bytes.

A curve A in FIG. 12 represents the block error rate of a 64-kilobyteunit as shown in FIG. 11, and a curve B represents the symbol errorrate. In FIG. 12, the horizontal axis represents the raw symbol errorrate and the vertical axis represents the corrected symbol error rate.

When the raw symbol error rate on the horizontal axis of FIG. 12 is at avalue of 4.0 E-3, the value of the corrected symbol error rate is foundto be approximately 1.0 E-16 from the curve B. This symbol error rate of1.0 E-16 is a value which realizes an almost error-free state (where noerrors occur). At this point, the block error rate of the 64-kilobyteECC block is approximately 7 E-12.

The values of the error rate shown in the graph of FIG. 10 are close toor sufficiently smaller than the value of the error rate represented bythe block error rate of the curve A in FIG. 12. That is, by carrying outthe above-described ECC block processing, an error rate substantiallyequal to the error rate in the data area 1B can be also realized in theburst cutting area 1A.

While four ECC blocks are recorded in the burst cutting area 1A in theabove-described example, it may be conceivable to record one ECC block,as shown in FIG. 13.

However, in the case where the number of ECC blocks is one, as shown inFIG. 13, multiple writing of disc ID and recording of different disc IDscannot be performed. If there is no need to perform multiple writing orrecording of a plurality of disc IDs, the number of ECC blocks may beone.

Giving an example of recording the disc ID information, a disc recordingdevice 11 for recording information in the burst cutting area 1A andultimately forming the optical disc 1 will now be described withreference to FIG. 14.

In FIG. 14, the disc ID information inputted via an input terminal IN isstored in a register 21. The register 21 is connected with an ECC (errorcorrecting code) circuit 20. The ECC circuit 20 generates an errorcorrecting code of a format shown in FIGS. 4 and 8 from the disc IDinformation stored in the register 21. The disc ID information which iserror correcting coded by the ECC circuit 20 is supplied to a 4/1modulating unit 22.

The 4/1 modulating unit 22 performs 4/1 modulation on the disc IDinformation read out from the register 21 in accordance with a clock(channel clock) inputted from a VCO (voltage-controlled oscillator) 33,the inserts a frame sync signal and the like to generate data to berecorded in the burst cutting area 1A of the optical disc 1, and outputsthe generated data to a laser 23.

The 4/1 modulation by the 4/1 modulating unit 22 is already describedwith reference to FIG. 2.

The laser 23 is, for example, a YAG laser or the like and casts ahigh-output laser beam onto the optical disc 1 via a mirror 24 and anobjective lens 25. The objective lens 25 includes, for example, acylindrical lens and casts the incident laser beam onto the burstcutting area 1A of the optical disc 1. Thus, the reflection film of theoptical disc 1 is irreversibly changed and the disc ID information isrecorded thereon.

A spindle motor 27 rotates the optical disc 1 under the control of aspindle servo control unit 28, and the spindle motor 27 causes an FG(frequency generator) signal generator to generate an FG signal as apulse every time the optical disc 1 (spindle motor 27) rotates by apredetermined angle and outputs the FG signal to the spindle servocontrol unit 28. The spindle servo control unit 28, under the control ofa controller 29, controls the spindle motor 27 so that the spindle motor27 rotates at a predetermined rotation speed, on the basis of the FGsignal inputted from the spindle motor 27. The spindle servo controlunit 28 also outputs the FG signal inputted from the spindle motor 27,to the controller 29 and a PC (phase comparator) 31.

The controller 29 controls the spindle servo control unit 28 inaccordance with an operation signal inputted from an operating unit, notshown, thus driving the spindle motor 27 and rotating the optical disc1. The controller 29 also generates a control signal for controlling thefrequency division ratio of a frequency divider 30 on the basis of theFG signal inputted from the spindle servo control unit 28 and outputsthe control signal to the frequency divider 30.

The frequency divider 30, the PC 31, a LPF (low-pass filter) 32 and theVCO 33 constitute a PLL (phase-locked loop).

The frequency divider 30 divides the frequency of the clock outputtedfrom the VCO 33 to a value 1/N (frequency division ratio) set on thebasis of the control signal inputted from the controller 29 and outputsthe clock to the PC 31. The PC 31 compares the phase of the clockinputted from the frequency divider 30 with the phase of the FG signalinputted from the spindle servo control unit 28 and thus generates andoutputs a phase difference signal to the LPF 32. The LPF 32 removes ahigh-frequency component from the inputted signal and outputs theresultant signal to the VCO 33. The VCO 33 changes the phase (frequency)of the clock to be oscillated and outputted, on the basis of the voltageapplied to the control terminal (that is, the output from the LPF 32).

The clock outputted from the VCO 33 is inputted to the 4/1 modulatingunit 22 and also inputted to the frequency divider 30, and the VCO 33 iscontrolled so that the phase difference between the output of thefrequency divider 30 and the FG signal outputted from the spindle servocontrol unit 28 is constant. Therefore, the output of the VCO 33 is asignal synchronously oscillating with a frequency which is N times thatof the FG signal. The 4/1 modulating unit 22 outputs to the laser 23 thedata of the format described above with reference to FIGS. 4 and 8, inaccordance with the clock inputted from the VCO 33.

The controller 29 is connected with a drive 34. On the drive 34, amagnetic disk 41, an optical disc 42, a magneto-optical disc 43 or asemiconductor memory 44 is appropriately loaded. The drive 34 reads out,for example, a necessary computer program and supplies it to thecontroller 29.

The operation of the disc recording device will now be described withreference the flowchart of FIG. 15. At step S11, the register 21acquires disc ID information from the input terminal IN and stores it.At step S12, the ECC circuit 20 codes the disc ID information for fourblocks by using RS(248, 216, 33), which is a Reed-Solomon code, asdescribed above with reference to FIGS. 4 and 8. The ECC circuit 20calculates parities at step S13 and forms ECC blocks at step S14.Specifically, error correcting coding is performed on the disc IDinformation by using a code which uses RS(248, 216, 33) per block andhas a long distance 33 with respect to the number of data 216, that is,a long distance code (LDC). Coding is performed with an inter-symboldistance which is achieved by increasing the proportion of the number ofparities to the number of data and thus improving the error correctioncapability. Moreover, since the above-described RS(248, 216, 33) ismultiple-written for four blocks at the most, the error correctioncapability is improved further.

The disc ID information recorded in the burst cutting area 1A of theoptical disc 1 relates to the entire data on the disc (for example,whether or not the encrypted content data recorded in the data area 1Bof the optical disc 1 may be decrypted and reproduced is determined). Tothis end, the disc ID information requires high reliability. Therefore,coding with high error correction capability must be performed on thedisc ID information, as described above. The error correction capabilityis equivalent to or higher than the error correction capability of errorcorrecting coding performed on the content data recorded in the dataarea 1B, as described above.

When the start of recording is commanded, the controller 29 at step S15controls the spindle servo control unit 28 to rotate the spindle motor27 at a constant angular velocity (CAV). The spindle motor 27 generatesan FG signal corresponding to the rotation and supplies the FG signal tothe spindle servo control unit 28. The spindle servo control unit 28supplies the FG signal to the PC 31.

At step S16, a channel clock is generated. Specifically, the PC 31compares the phases of two input signals with each other and supplies aresultant phase different signal to the VCO 33 via the LPF 32. The VCO33 generates a channel clock having a phase and frequency correspondingthe signal (controlled voltage) supplied from the LPF 32. The clockoutputted from the VCO 33 is supplied to the frequency divider 30, wherethe clock is frequency-divided by a predetermined frequency divisionratio set via the controller 29 and the frequency-divided clock issupplied to the PC 31.

In the above-described manner, the VCO 33 performs PLL so as to realizesynchronization with one rotation of the optical disc 1, and thusgenerates and outputs a channel clock having a frequency which is Ntimes the frequency of the FG signal from the spindle motor 27.

For example, if the frequency of the FG signal per rotation is 50 andthe value of the frequency division ratio 1/N at the frequency divider30 is 1/95, a channel clock having 1/4750 cycles, which is 1/(50×95) ofthe time of one rotation of the spindle motor 27 (optical disc 1), isgenerated.

At step S17, the 4/1 modulating unit 22 performs 4/1 modulation on thedisc ID information to which the error correcting code is added by theECC circuit 20, on the basis of the channel clock supplied from the VCO33, and supplies the 4/1-modulated data to the laser 23. At step S18,the laser 23 generates a laser beam on the basis of the data (recordedchannel bits) supplied from the 4/1 modulating unit 22 and casts thelaser beam onto the optical disc 1 via the mirror 24 and the objectivelens 25. In this manner, at the time of shipment from the plant, thedisc ID information is recorded, for example, concentrically, over aplurality of tracks in the burst cutting area 1A of the optical disc 1.

When the duty of the mark of the recorded channel bits is to be lowered,for example, when only 10 μm of the channel bit length of 30 μm is to beused as the mark (FIG. 3), the VCO 33 is oscillated at a frequency whichis three times that of the channel clock so that only one of threeclocks equivalent to the channel bits may be used as the mark.

In the burst cutting area 1A of the optical disc 1, the same disc IDinformation is entered for four blocks, as described above. By doing so,the information can be obtained even when one of the four blocks cannotbe read. In the case of quadruple writing, even when a large dustparticle is adhered over two codes (blocks), the other two blocks areavailable and therefore an error can be corrected. Alternatively,different disc ID information is recorded in two or more blocks. Bydoing so, it is possible to manage the same optical disc 1 by four typesof different applications at the maxim.

FIG. 16 is a block diagram showing the structure of a discrecording/reproducing device 60 for recording main data into the dataarea 1B of the optical disc 1 which has the disc ID information recordedin its burst cutting area 1A as described above, and for reproducing therecorded main data.

A CPU 61 controls each part of the disc recording/reproducing device 60in accordance with an operation signal inputted from an operating unit,not shown, in order to record main data into the data area 1B of theoptical disc 1 and reproducing the recorded main data. When reproducingor recording data, the CPU 61 causes the disc ID information on theoptical disc 1 held by a register 71 to be outputted to a decryptionprocessing unit 74 or an encryption processing unit 75, and generatesand outputs a control signal for instructing rotation or stop of theoptical disc 1 to a servo control unit 63.

The servo control unit 63 causes an optical pickup 64 to seeks apredetermined position on the optical disc 1 on the basis of the controlsignal inputted from the CPU 61, and carries out tracking control andfocusing control of the optical pickup 64 on the basis of a trackingerror signal (TK) and a focusing error signal (FS) supplied from amatrix amplifier (MA) 65. A spindle motor 62 rotates the optical disc 1at a predetermined rotation speed under the control of the servo controlunit 63.

In reproducing the disc ID information, the servo control unit 63rotates the optical disc 1 in accordance with the CAV (constant angularvelocity) mode. In recording and reproducing the main data, the servocontrol unit 63 rotates the optical disc 1 in accordance with the CLV(constant linear velocity) mode.

The optical pickup 64 is held by a predetermined thread mechanism sothat is movable in the radial direction of the optical disc 1. When thedata recorded on the optical disc 1 is to be recorded, the opticalpickup 64 casts a laser beam onto the optical disc 1 in accordance witha control signal inputted from the servo control unit 63, then receivesits reflected beam, converts it to an electric signal, and outputs thesignal to the matrix amplifier 65. When new data is to be recorded ontothe optical disc 1, the optical pickup 64 casts a laser beam onto theoptical disc 1 on the basis of data outputted from a modulating unit 77and causes the data to be recorded in the data area 1B of the opticaldisc 1.

The matrix amplifier 65 processes the signal inputted from the opticalpickup 64 and outputs a reproduced signal of the data corresponding tothe disc ID information recorded in the burst cutting area 1A to a LPF66. The matrix amplifier 65 also generates a tracking error signal withits signal level changed in accordance with the quantity of trackingerrors and a focusing error signal with its signal level changed inaccordance with the quantity of focusing errors, then outputs thetracking error signal and the focusing error signal to the servo controlunit 63, and outputs a reproduced signal of the data recorded in thedata area 1B to a demodulating unit 72.

The LPF 66 restrains the variance in the reproduced signal due to noiseby removing a high-frequency component from the inputted signal andoutputs the resultant signal to a comparator 67. The comparator 67compares the inputted signal with a predetermined level, therebybinarizing the signal. A demodulating unit 68 samples the inputtedsignal on the basis of a sampling clock inputted from a crystaloscillator 69, performs channel position correction and demodulation (inthis case, 4/1 demodulation) on the signal, and outputs the resultantsignal to an ECC unit 70. The number of sampling clocks is a numericalvalue based on the disc ID recording format. The ECC unit 70 performserror correction processing on the inputted demodulated data (disc IDinformation) on the basis of the error correcting code (RS(248, 216,33)) contained in the disc ID information and causes the register 71 tostore the error-corrected disc ID information. The ECC unit 70 and anECC unit 73, which will be described later, may be a single common ECCunit.

Meanwhile, the demodulating unit 72 demodulates the data (content data)supplied from the matrix amplifier 65 and supplies the demodulated datato the ECC unit 73. The ECC unit 73 performs error correction on theinputted demodulated data (for example, coded by RS(248, 216, 33)) byusing 32 parities and then supplies the error-corrected data to thedecryption processing unit 74. The decryption processing unit 74decrypts the content data supplied from the ECC unit 73 on the basis ofthe disc ID information supplied from the register 71 and outputs thedecrypted data to a device, not shown.

The encryption processing unit 75 encrypts content data inputted forrecording on the basis of the disc ID information supplied from theregister 71 and outputs the encrypted data to an ECC unit 76. The ECCunit 76 codes the inputted encrypted data by using RS(248, 216, 33) andoutputs the coded data to the modulating unit 77.

In a drive 81, a magnetic disc 91, an optical disc 92, a magneto-opticaldisc 93 or a semiconductor memory 94 is loaded, when necessary. Thedrive 81 supplies a program read out from the medium to the CPU 61.

The operation in data recording will now be described with reference toFIG. 17. When the optical disc 1 is loaded in the discrecording/reproducing device, the CPU 61 executes BCA reproductionprocessing at step S31. This BCA reproduction processing is described indetail in FIG. 18.

Specifically, at step S51, the CPU 61 controls the servo control unit 63to rotate the spindle motor 62 at a constant angular velocity (inaccordance with the CAV mode). The velocity is the same as the velocityin the case where the spindle motor 27 of the disc recording device ofFIG. 14 rotates the optical disc 1.

At step S52, the servo control unit 62 moves the optical pickup 64 inthe radial direction of the optical disc 1 and causes the optical pickup64 to reproduce the data in the burst cutting area 1A of the opticaldisc 1.

At step S53, demodulation processing is carried out. Specifically, thereproduced data outputted from the optical pickup 64 is inputted to thecomparator 67 via the matrix amplifier 65 and the LPF 66 and isbinarized there. The demodulating unit 68 samples the binary datainputted from the comparator 67 on the basis of the sampling clocksupplied from the crystal oscillator 66 and demodulates the binary data.The demodulating unit 68 also carries out processing to correct thechannel bits and word. The demodulated data of four blocks outputtedfrom the demodulating unit 68 is supplied to the ECC unit 70.

At step S54, the ECC unit 70 performs error correction processing on thedemodulated data of four blocks in total. Specifically, the ECC unit 70executes ECC decoding processing by using the fixed data of 200 bytesdescribed with reference to FIG. 6 for each block, and by using pointererasure processing on the assumption that the parities of the latter 16bytes of the parties of 32 bytes have been erased.

At step S55, the CPU 61 reads the header of the block on which errorcorrection processing has been performed by the ECC unit 70. Asdescribed above with reference to FIG. 8, application ID of 6 bits isstored as BCA content data in the header. The CPU 61 extracts theapplication ID from the header, and at step S56, determines whether ornot this application ID is available to the CPU 61 itself. If it isdetermined that the application ID thus read is not available to the CPU61 itself, the CPU 61 cannot record data to or reproduce data from theoptical disc 1. Therefore, the CPU 61 goes to step S62 and executeserror processing. For example, the CPU 61 causes a display unit, notshown, to display a message like “this disc cannot be used.”

If it is determined at step S56 that the application ID is available,the CPU 61 goes to step S57 and selects a block having the availableapplication ID from the four blocks.

At step S58, the CPU 61 determines whether or not the disc ID has beenmultiple-written from the application ID and the block number. If thedisc ID has been multiple-written, the CPU 61 goes to step S59 andselects one of the blocks in which multiple writing has been carriedout. For example, if error correction cannot be carried out in the blockselected by the processing of step S57, the CPU 61 selects another blockin which multiple writing has been carried out (another block which hasa header with the sane (corresponding) application ID and block numberrecorded therein and can be error-corrected). If it is determined atstep S58 that disc ID has not been multiple-written, the processing ofstep S59 is skipped. That is, in this case, the block selected at stepS57 is the only block to be selected as the reading object.

Next, at step S60, the CPU 61 extracts the disc ID of the block selectedby the processing of step S57 or step S59. Specifically, the disc ID ismade up of the content data of FIG. 8. Having extracted the disc ID, theCPU 61 at step S62 controls the ECC unit 70 to store the disc ID in theregister 71.

In this manner, if the loaded optical disc can be used, the disc IDinformation recorded in the burst cutting area 1A of the optical disc 1is error-corrected and stored in the register 71.

Referring again to FIG. 17, at step S32, the CPU 61 controls the servocontrol unit 63 to rotate the optical disc 1 via the spindle motor 62 inaccordance with the CLV mode. At step S33, the encryption processingunit 75 reads the disc ID information stored in the register 71.

At step S34, the encryption processing unit 75 encrypts content data forrecording inputted from a device, not shown, on the basis of the disc IDinformation read from the register 71, and outputs the encrypted contentdata to the ECC unit 76. At step S35, the ECC unit 76 codes the contentdata inputted from the encryption processing unit 75 by using RS(248,216, 33) and outputs the coded content data to the modulating unit 77.At step S36, the modulating unit 77 modulates the coded content datainputted from the ECC unit 76 in accordance with a predeterminedmodulation mode and outputs the modulated content data to the opticalpickup 64. At step S37, the optical pickup 64 records the content datainputted from the modulating unit 77 into the data area 1B of theoptical disc 1.

The processing for reproducing content data will now be described withreference to the flowchart of FIG. 19.

First, at step S81, the BCA reproduction processing is executed. Thisprocessing similar to the processing shown in FIG. 18.

If the disc ID of the corresponding application ID is already stored inthe register 71, this BCA reproduction processing can be omitted.However, if the application ID differs, the BCA reproduction processingis executed again.

The processing goes to step S82 and the CPU 61 executes the processingto reproduce data from the data area 1B.

Specifically, the CPU 61 controls the servo control unit 63 to rotatethe optical disc 1 in accordance with the CLV mode similarly to theabove-described case. The optical pickup 64 reproduces data in the dataarea 1B of the optical disc 1 and outputs the reproduced data to thematrix amplifier 65. The matrix amplifier 65 supplies the reproduceddata to the demodulating unit 72.

At step S83, the demodulating unit 72 demodulates the reproduced contentdata inputted thereto in accordance with a demodulation modecorresponding to the modulation mode at the modulating unit 77, andoutputs the demodulated data to the ECC unit 73. At step S84, the ECCunit 73 performs error correction processing on the demodulated datainputted from the demodulating unit 72 by using RS(248, 216, 33) asdescribed above and then supplies the error-corrected data to thedecryption processing unit 74. The decryption processing unit 74, atstep S85, reads the disc ID stored in the register 71, and at step S86,decodes the content data (encrypted content data) inputted from the ECCunit 73 on the basis of the disc ID information read from the register71 and outputs the decoded data to a device, not shown.

The content data is encrypted and then recorded in the data area 1B ofthe optical disc 1 as described above. Even when the encrypted contentdata is directly copied to another disc by a computer or the like, thedisc ID information cannot be copied and the content data cannot bedecrypted. Therefore, unauthorized copying of a large quantity of datacan be substantially restrained.

In reproducing the disc ID information, it is assumed that thereproducing operation is carried out without performing tracking servo.Therefore, if the reproducing operation is carried out repeatedly over aplurality rotations of the optical disc 1, the radial position might beslightly shifted, generating different results of reproduction(reproduced data). Thus, the reproducing operation or correctingoperation can be carried out over a plurality of rotations.

While disc ID is recorded as content data in the above description,auxiliary data other than disc ID may be recorded.

The present invention may also be applied to CD (compact disc), MD (minidisc: trade name by Sony Corporation) and DVD (digital versatile disc)as well as the above-described optical disc.

The above-described series of processing can also be executed bysoftware. The software may be installed from a recording medium, forexample, to a general-purpose personal computer which is capable ofexecuting various functions, by installing a program constituting thatsoftware into a computer embedded in dedicated hardware, or byinstalling various programs.

The recording medium is constituted by a package medium such as themagnetic disk 41, 91 (including a flexible disk), the optical disc 42,92 (including CD-ROM (compact disc-read only memory), DVD (digitalversatile disc)), the magneto-optical disc 43, 93 (including so-calledMD (mini disc: trade name by Sony Corporation)) or the semiconductormemory 44, 94, on which the program is recorded and which is distributedfor providing the program to a user, separately from the computer, asshown in FIG. 14 or FIG. 16.

In this specification, the steps describing the program recorded on therecording medium include the processing which is not necessarily carriedout in time series but is executed in parallel or individually, as wellas the processing carried out in time series in accordance with thedescribed order.

Moreover, in this specification, the system refers to a whole deviceconstituted by a plurality of devices.

While the invention has been described in accordance with certainpreferred embodiments thereof illustrated in the accompanying drawingsand described in the above description in detail, it should beunderstood by those ordinarily skilled in the art that the invention isnot limited to the embodiments, but various modifications, alternativeconstructions or equivalents can be implemented without departing fromthe scope and spirit of the present invention as set forth and definedby the appended claims.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, an error of theBCA code can be securely corrected.

According to the present invention, high error correction capability canbe realized and the reliability of the acquired information can beimproved.

According to the present invention, the hardware for error correctionprocessing can be made common, thus realizing simplification of thestructure and reduction in cost.

The quantity of recorded error correcting codes can be reduced and thescanning density can be increased, thus improving the reliability.Moreover, it is possible to increase the recording capacity.

1. An information reproducing device for reproducing main data from adisc recording medium having a data area in which the main data isrecorded and a burst cutting area in which auxiliary information isrecorded, the device comprising: acquisition means for acquiring theauxiliary information recorded in the burst cutting area, the auxiliaryinformation being blocked to generate error correction blocks, using anerror correcting code that is the same as an error correction code RS(m,n,k) of the main data recorded in the data area, with data having alength d which is smaller than the n and fixed data having the remaininglength n-d; reproduction means for reproducing the main data from thedata area; demodulation means for demodulating the main data reproducedby the reproduction means; and decoding means for decoding the main datademodulated by the demodulation means on the basis of the auxiliaryinformation acquired by the acquisition means.
 2. The informationreproducing device as claimed in claim 1, wherein only a part ofparities having a length of k−1 of the error correction blocks isencoded.
 3. The information reproducing device as claimed in claim 2,wherein only parities of (k−1)/2, which are a part of parities having alength of k−1, of the error correction blocks are encoded.
 4. Theinformation reproducing device as claimed in claim 1, wherein the errorcorrecting code RS(m,n,k) is RS(248, 216, 33).
 5. The informationreproducing device as claimed in claim 1, wherein if the plurality oferror correction clocks are recorded on the disc recording medium, theacquisition means selects a predetermined error correction block on thebasis of the identification number and the block number recorded in aheader of the error correction blocks and acquires the auxiliaryinformation of the selected error correction block.
 6. The informationreproducing device as claimed in claim 4, wherein if an error of theselected error correction block of the plurality of error correctionblocks cannot be corrected, the acquisition means selects another errorcorrection block having the corresponding identification number andblock number.
 7. An information reproducing method for an informationreproducing device which reproduces main data from a disc recordingmedium having a data area in which the main data is recorded and a burstcutting area in which auxiliary information is recorded, the methodcomprising: an acquisition step of acquiring the auxiliary informationrecorded in the burst cutting area, the auxiliary information beingblocked to generate error correction blocks, using an error correctingcode that is the same as an error correction code RS (m,n,k) of the maindata recorded in the data area, with data having a length d which issmaller than the n and fixed data having the remaining length n-d; areproduction step of reproducing the main data from the data area; ademodulation step of demodulating the main data reproduced by theprocessing of the reproduction step; and a decoding step of decoding themain data demodulated by the processing of the demodulation step on thebasis of the auxiliary information acquired by the processing of theacquisition step.
 8. A recording medium having a computer-readableprogram recorded thereon, the program being adapted for an informationreproducing device which reproduces main data from a disc recordingmedium having a data area in which the main data is recorded and a burstcutting area in which auxiliary information is recorded, the programcomprising: an acquisition step of acquiring the auxiliary informationrecorded in the burst cutting area, the auxiliary information beingblocked to generate error correction blocks, using an error correctingcode that is the same as an error correction code RS (m,n,k) of the maindata recorded in the data area, with data having a length d which issmaller than the n and fixed data having the remaining length n-d; areproduction step of reproducing the main data from the data area; ademodulation step of demodulating the main data reproduced by theprocessing of the reproduction step; and a decoding step of decoding themain data demodulated by the processing of the demodulation step on thebasis of the auxiliary information acquired by the processing of theacquisition step.
 9. A program executable by a computer which controlsan information reproducing device for reproducing main data from a discrecording medium having a data area in which the main data is recordedand a burst cutting area in which auxiliary information is recorded, theprogram comprising: an acquisition step of acquiring the auxiliaryinformation recorded in the burst cutting area, the auxiliaryinformation being blocked to generate error correction blocks, using anerror correcting code that is the same as an error correction code RS(m,n,k) of the main data recorded in the data area, with data having alength d which is smaller than the n and fixed data having the remaininglength n-d; a reproduction step of reproducing the main data from thedata area; a demodulation step of demodulating the main data reproducedby the processing of the reproduction step; and a decoding step ofdecoding the main data demodulated by the processing of the demodulationstep on the basis of the auxiliary information acquired by theprocessing of the acquisition step.